Light signal system for railroads



Dec. 29, 1936. o. H. DlcKE LIGHT SIGNAL SYSTEM FOR RAILROADS Filed Aug. 16, 1929 V n. im 6 BY N Y.

1 /ATTQRNEY Patented Dec. 29, 1936 LIGHT SIGNAL SYSTEM FOR RAILROADS Oscar H. Dicke, Rochester, N. Y., asslgnor to General Railway Signal Company, Rochester,

Application August 1s, 1929, serial No. 383,300

13 Claims.

The present invention relates to light signal systems for railroads, and more particularly to means for indicating at a local point the illumination of a lamp in a particular signal unit located at a distant point.

l'br reasons well understood by those skilled inthe art of railway signalling. it is essential to indicate reliably the illumination of a stop or danger lamp on a particular route when such stop or danger lamp is actually illuminated, this in order to avoid movement of trains on conilicting routes simultaneously.

In accordance with the present invention it is proposed to indicate the illumination of a danger or stop lamp by including in series therewith suitable unl-directional resistances or rectifying means, and to have such rectifying means located so near the lamp itself, that the flow of unl-directional current in a circuit to which alternating current is applied may be relied upon to manifest the flow of this direct current through such signal lamp and to manifest illumination of such lamp. v

'Other objects, purposes, and characteristic features of the present invention reside in the provision of a single circuit connecting a local interlocking tower and distant signal location, which single circuit is used for-both controlling a distant signal and receiving indication as to the illumination of the signal light of such distant signal. Other objects, purposes and characteristic features of the present invention `will in part be obvious from the accompanying drawing and will in part be pointed out in the description hereinafter.

In describing the invention in detail reference will be made to the accompanying drawing, in which:

Fig. l shows one embodiment of the present invention in which a rectifier signies the pathsthrough' which the alternating current is flow- Referring to Fig. 1 of the drawing, with 'the lever L in the normal danger position the following circuit is closedz-beginning at the secondary winding of the transformer i0, wire Il;

contact l2 of the lever L, wire I3, indicating relay DC. responsive only tothe flow of direct current, line wire Il, distant danger signal unit R, rectifier RE, wire II, and common return wire C and back to the transformer I0. With this circuit properly intact there will be flowing a certain amount of direct current depending on the construction of the rectifier RE, but such 5 direct current will only flow in the event that the circuit in question actually includes the rectifler RE, and if this is the case, it may be conclusively presumed that the circuit also includes the incandescent lamp of the red signal unit R. 10 The flow ofthis direct current in said circuit will cause the contacts of indicating relay DC t0 assume energized positions, thereby illuminating the indicating lamp I through the front vcontact i6 of this relay. and thereby closing a circuit 15 through a suitable lever leading to the proceed signal of a conflicting route through route through the medium of contact Il.

It is thus seen that a relay DC, which will not respond to alternating current'. will only be enl0 ergized in the event that current is flowing though the signal lamp R. Carrying this theory a little further, let us assume that a cross accldentally occurs between the line wire I4 and the common return wire C. The presence of such a cross would allow current to flow through the contact 'I2 of the lever L, and through the relay DC but since this current would be entirely alternating in character, the indicating relayDCwould remain in its de-energized position and the conicting route could not be set up. With, the lever L inv its dotted abnormal position the danger lamp R is of course extinguished and the 'relay DC will assume its de-energized position. thereby extinguishing the indicating lamp I and preventing the signals of conflicting routes being cleared. Also if the filament of the stop signal R burns out the relay DC will be de-energized.

Referring now to Fig. 2 of the drawing, let us assume that a lever Ll assumes its reverse pro- 40 v ceed position, as shown, in the drawing, in which case the following circuit-for the signal relay SR is closedz-beginning at the transformer 20, wire 2|, contact 22 of the lever L1, .wires 23 and 25, v

condenser 26, signal relay SR, wire 21. common return wire C, and back to the secondary winding of' transformer 20. Closure of this circuit causes the relay SR to assume its energized position, thereby completing the following circuit for the proceed'green lamp G:-beginning at the second- 5G With this latter circuit closedv the proceed lamp G will be illuminated, thereby allowing traffic to Let us now assume that the lever L1 is moved to its normal danger position, indicated by 'dotted lines, thereby effecting de-energization of the signal relay SR. With the signal relay SR deenergized the following circuit for the red lamp R is closedz-beginning at the secondary winding 3i of the transformer 29, back contact 40 of the relay SR, wire 4|, rectifier unit 42, red lamp R, wire 43, inductance 35, line wire 25, wire 44, indieating relay DC1, wire 45,contact 22, wire 46, common return wire C, wire 41, rectifying unit 48, wire 49 back to the secondary `winding- 3i. Current flows in the circuit just traced during one wave of the alternating current cycle, and during the period of the other wave of the alternating current cycle current ilows as follows:- beginning at the secondary winding 3l, wire 49, rectifying unit 50, red lamp R, wire 43, inductance 35, line wire 25, wire 44, relay DC1, wire 45, contact 22, wire 46, common return wire C, wire 41, rectifying element 5I, wire 4I, back contact 40, and back to the secondary winding 3|.

It thus appears that the secondary winding 3l supplies the energy of the double wave rectiiler RE1, which rectifier in turn applies direct current to the red lamp R, which direct current flows freely through the inductance 35 and the direct current relay DC1. The flow of this direct l current causes the indicating relay DC1 to assume its energized position and effect illumination of the indicating lamp I1, through the medium of front Contact 5s, and closes the circuit to the signal of the conflicting route, through the medium of the contact 54.

In practicing the present invention the rectiiler RE1 should be located so near the red lamp R that the ilow of direct current through the indication circuit, including the relay DC1, may be relied upon to also ilow through'the red lamp R, thereby assuring that the red lamp R is actually illuminated in the event direct current flows over the indication circuit.

In other words, if the lamp R should burn out, which is the cost common failure of an incandescent lamp, no uni-directional indication current will flow back to the interlocking tower and the indicating relay D01 will be de-energized, thusinforming the tower .man that the red lamp R is extinguished, and thereby preventing the illumination of a proceed signal of a conflicting route.

Attention is also directed to` the fact that an unauthorized cross between the wires 25 and C will eilect de-energization of the indicating relay DC1 and the extinguishment of the indicating4 lamp i1. Putting it briefly, the line circuit 25-C has alternating current transmitted thereover to effect energization of the proceed lamp and also constitutes the circuit for energizing the danger or stop lamp R. Further the stop lamp is energized by direct current whereas the proceed lamp is energized by alternating current, d the indicating relay responds only to dir t ,current. It thus appears that the system is not only safe in that it cannot give an indication of illumination of the danger lamp by reason of a cross or a ground, or the like, but is economical in the use of line wires. Also, if desired, the indicating relays DC and DC1 may be of the polar type to give a further assurance that the circuit operating the same isnot a foreign and unauthorized one. l

Having thus shown and described several embodiments of the present invention, it is to be vunderstood that these illustrations are merely exemplincations of the invention and are not to be construed as the exact constructions preferably employed in practicing the invention, and that changes, modiiications Aand additions may be made to adapt the invention to the particular problem encountered in practicing the same, all

without departing from the spirit and scope oi' 1s the invention, except as demanded by the scope of the following claims. 4

l. A light signal system for railroads comprising; a. distant light signal including an incana0 descent lamp; a rectier unit separate from said lamp and connected in series with said lamp: a local lever; a local direct current relay; a source of alternating current;` a circuit including said lamp, said rectifier. said lever, said relay and 25 said source of alternating current in series closed if said lever assumes a particular position; and

Iindicating means controlled by said direct current relay.

2. A light signal system for railroads comprising; a distant control relay responsive only to a1-4 ternating current, a local source of alternating current, a line wire connecting said local and distant point, a lever for applying said alternating current source to said relay to energize said relay, a proceed light signal, means for energizing said proceed signal when said relay is energized, a stop light signal. a circuit for energizing said stop signal with direct current closed when said lrelay is de-energized, an indicating relay at 40 said local point responsive only to direct current and included in said circuit. y

3. A light signal system for railroads comprising; a distant control relay responsive only to alternating current, a localsource of alternating current, a line wire connecting said local 'and' said relayfa proceed light signal, means for energizing said proceed signal when said relay is energized, a stop light signal, a circuit including said line wire for energizing said stop signall with direct current closed when said relay is de-energized, and an indicating relay at said .local point responsive only to direct current and included in' said circuit.

4. A light signal system for railroads comprising, a distant control relay responsive only to alternating current, a local source oi' alternating current, a line wire connecting said local and a0 distant point, a lever for applying said alternating current source to said relay to energize said relay,

a proceed lightvsignal, means for energizing said proceed signal when said relay is energized, a stop light signal, a circuit for energizing said stop signal, a rectiner adiacent'and external tosaid stop signal and connected in series therewith, and an indicating relay at said local point responsive only to direct current and included in said circuit. d '10 5. A light signal system for railroads comprising, a distant control relay responsive only to alternating current, a local source of alternating current, a line wire connecting said local and distant point, a lever for applying said alternating 1| current source .to said relay to energize said relay, a proceed light signal, means for energizing said proceed sig-nal by alternating current when said relay is energized, a stop light signal, a circuit including said line wire for energizing said stop signal, a rectiiier external to said stop signal but connected in series therewith, and an indicating relay at said local point responsive only to direct current and included in said circuit.

6. In combination, a distant signal lamp for controlling trailic movements on a railroad, a circuit controlled from a local point for energizing said lamp by an electric current, means in said circuit in series with and near said lamp for Achanging said current to a current lof different character, and means at said local point for inydicating whether said current has been so changed.

7. In an interlocking system 'for railroads, the combination with a. local lever, of a distant proceed signal lamp and a distant stop signal lamp, a circuit connecting said lever and distant signals,

means for lighting said distant proceed lamp in response to current of oney character applied at the lever end of said circuit and vapplying current of another character to said stop lamp from the signal end of said circuit, and indicating means at said lever in said circuit for detecting the iiow of said current of another character in -said circuit.

8. In an interlocking system for railroads, the

" combination with a local lever, of a distant proceed signal lamp and a distant stop signal lamp,

a circuit connecting said lever and distant sig-A nals, means for -lighting said distant proceed lamp in response to current of one character applied at the lever end of said circuit and applying fcurrent of another character to said stop 4lamp from the signal end of said circuit, indicating means at said lever in said circuit for detecting the ilow of said current of another character in said circuit, and means for permitting energization of a proceed signal of a conflicting route governed by said indicating means.

9. In an interlocking system for railroads, the' combination with a local lever, of a distant proceed signal lamp and a distant stop signallamp,

a circuit connecting said lever and distant sig nal, means for lighting said distant proceed lamp in response to current of one character applied at the lever end of said circuit and applying current of another character to said st op lamp from the signal end oi' said circuit, and indicating means at said level` in said circuit i'ordetecting the ilow of said current of another character in said cirif said relay assumes its deenergized position and said lever assumes its stop position.

11. In combination, a lever having a proceed position land a stop position, a control relay, a source of current at said lever, a proceed signal lamp, a stop signal lamp, a line wire, a circuit for energizing said relay including said line wire, and said source and closed if said lever is in the proceed position, a circuit for said proceed lamp closed if said relay is energized, and a circuit for said stop lamp including a distinctive source of current, said line wire and closed if said relay assumes its deenergized position and said lever assumes its stop position.

l2. In combination, a lever having a proceed position and a stop position, a control relay, a

lamp, a stop signal lamp, a line wire, a circuit for energizing said relay including said line wire, and said source and closed if said lever is in the proceed position, a circuit for said proceed lamp closed if said relay is energized, a circuit for said stop lamp including a distinctive source of current, said line wire and closed if said relay assumes its deenergized position and said lever assumes its stop position, and iilter means for isolating said distinctive source from said relay.

13. In combination, a distant signal lamp for controlling traiilc movements on a railroad, a circuit controlled from a local point for energizing said lamp by an electric current, means in said circuit in series with and adjacent, said lamp, and separate from said lamp, for changing said current to a current of different character through said lamp, and means at said local point forindicating whether said current has been changed.

' OSCAR H. DICKE.

'30 v source of current at said lever, a proceed signal 

